• ETRI Journal
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• v.25 no.2
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• pp.144-147
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• 2003

We propose a new serial concatenation scheme for space-time and recursive convolutional codes, in which a space-time code is used as the outer code and a single recursive convolutional code as the inner code. We discuss previously proposed serial concatenation schemes employing multiple inner codes and compare them with the new one. The proposed method and the previous one with joint decoding, both performing a combined decoding of the simultaneous output signals from multiple antennas, give a large performance gain over the separate decoding method. In decoding complexity, the new concatenation scheme has a lower complexity compared with the multiple encoding/joint decoding scheme due to the use of the single inner code. Simulation results for a communication system with two transmit and one receive antennas in a quasi-static Rayleigh fading channel show that the proposed scheme outperforms the previous schemes.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.1-3
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• 1998

The 21st century will see the formation of a“Cyber society”that, while separate form the real world, will cooperate with it, leading to the further expansion and development of world society. Cyber society allows the formation of virtual space through the connection of multiple computers in a network. In this virtual space, multiple users can communicate with each other and can collect and exchange information while moving about freely and engaging in activities. Three main technologies are vital to the construction of the Cyber society: platform technology for converting multimedia information to optical signals and performing digital processing and communication processing on such signals; communications network technology for transferring these signals from one point to another; and application technology for configuring the Cyber society that will be formed on this network. This paper describes platform technology and network technology with an emphasis on their relationship to application technology for configuring the Cyber society, and will also discuss InterSpace, one of the cyber society platform system of the Cyber society.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.128.1-128.1
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• 2011

We present the results of the first simultaneous dual-frequency VLBI observation with KVN (Korean VLBI Network). The KVN has a unique multi-frequency receiving system performing simultaneous observations at four frequencies, such as 22, 43, 86, and 129 GHz, in order to calibrate the atmospheric phase fluctuations, which cause a severe degradation of an interferometric coherence in mm-VLBI regime. In order to test the multi-frequency phase referencing capability of KVN, we observe the bright continuum VLBI source, NRAO 150 at two different frequencies of 21.7 (K band) and 43.4 (Q band) GHz simultaneously. The VLBI fringe phases at K and Q bands show a tight correlation of phase behaviors and the results of phase referencing (residual phase, coherence etc) are promising for achieving excellent phase referencing observations with KVN. The KVN will be able to open new perspectives in the multi-frequency study of VLBI.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.46.3-47
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• 2016

We construct a solar eruption model with a background solar wind by performing three-dimensional zero-beta magnetohydrodynamic (MHD) simulation. The initial configuration of a magnetic field is given by nonlinear force-free field (NLFFF) reconstruction applied to a flux emergence simulation. The background solar wind is driven by upflows imposed at the top boundary. We analyzed the temporal development of the Lorentz force at the flux tube axis. Based on the results, we demonstrate that a solar eruption is caused by the imbalance between magnetic pressure gradient force and magnetic tension force. We conclude that this imbalance is produced by a weak but continuously existing solar wind above an active region.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.5
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• pp.359-366
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• 2019

Indoor spatial data has great importance as the demand for representing the complex urban environment in the context of providing LBS (Location-based Services) is increasing. IndoorGML (Indoor Geographic Markup Language) has been established as the data standard for spatial data in providing indoor navigation, but its definitions and relationships must be expanded to increase its applications and to successfully delivering information to users. In this study, we propose an approach to integrate IndoorGML with Indoor POI (Points of Interest) data by extending the IndoorGML notion of space and topological relationships. We consider two cases of representing Indoor POI, by 3D geometry and by point primitive representation. Using the concepts of the NRS (node-relation structure) and multi-layered space representation of IndoorGML, we define layers to separate features that represent the spaces and the Indoor POI into separate, but related layers. The proposed methodology was implemented with real datasets to evaluate its effectiveness for performing indoor spatial analysis.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.207-209
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• 2020

최근 문화예술에 대한 관심이 증가되고 있다. 특히 지역의 발전과 수익, 지자체의 활성화를 위해 "마을문화공간 활용"에 대한 이슈가 집중되고 있으며, 특히 유휴공간을 활용한 활동들이 많이 이뤄지고 있다. 이 논문을 통해서 지자체와 지역민들이 활용할 수 있는 전략방안을 제시하고자 한다.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.217-224
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• 2023

The Korea Pathfinder Lunar Orbiter (KPLO), also known as Danuri, successfully entered its mission orbit on December 27, 2022 (UTC), and is currently performing its mission smoothly. To mitigate potential contingencies during the flight and to navigate the spacecraft into the desired lunar orbit, the KPLO flight dynamics (FD) team analyzed major trajectory-related contingencies that could lead to the violation of mission requirements and prepared operational procedures from the perspective of trajectory and FD. This paper presents the process of preparing contingency trajectory operations for the KPLO, including the identification of trajectory contingencies, prioritization results, and the development of recovery plans and operational procedures. The prepared plans were successfully applied to address minor contingencies encountered during actual operations. The results of this study will provide valuable insights to FD engineers preparing for space exploration mission operations.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.327-334
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• 2013

The purpose of this study is to develop an observation program for obtaining effective flat images that are necessary for photometric observation. The development of the program was achieved by improving the existing method for obtaining twilight flat images. The existing method for obtaining twilight flat images acquires flat images by observing the sky light after sunset or light before sunrise. The decision of when to observe flat images at each night is solely dependent on the judgment of an observer, and thus the obtained flat images for particular nights may not be clean. Especially, in the case of the observatories where an automated observation system is in operation, there is a difficulty that an observer should pay attention during sunrise and sunset in order to obtain flat images. In this study, a computer program is developed to improve this inconvenience and to efficiently perform photometric observation in the observatories where an automated observation system is applied. This program can obtain flat images by calculating the time for obtaining flat images automatically and the exposure time using a numerically calculated function. When obtaining twilight flat images at dusk and at dawn, the developed program performs automated observation and provides effective flat images by acquiring appropriate exposure time considering the sunrise and sunset times that vary depending on the day of observation. The code for performing this task was added to Obs Tool II (Yoon et al. 2006), which is the automated observation system of the Chungbuk National University Observatory, and the usefulness of the developed program was examined by performing an actual automated observation. If this program is applied to other observatories where automated observation is in operation, it is expected that stable and high-quality flat images could be obtained, which can be used for the pre-processing of photometric observation data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.3
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• pp.110-114
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• 2016

Newly constructed multi-residential buildings with more than 500 households should be flushed out indoor contaminants using a mechanical ventilation system or large fans after the completion of construction and prior to occupancy by the Heath-friendly Housing Construction Standards since 2014. In addition, the standard recommends to maintain indoor temperature over $16^{\circ}C$ and relative humidity below 60% while performing the flush-out. However, it is difficult to maintain these recommended indoor conditions, especially during winter season because additional energy cost is needed for space heating. Therefore, in this study, additional energy cost including heating and ventilation energy cost in multi-residential household for flush-out during winter season was estimated using building energy simulation program called EnergyPlus. Additional energy cost according to various conditions for performing flush-out (such as performance period, ventilation rate, and heating set-point temperature) was analyzed. Based on the results of the energy simulation, the energy cost was estimated to be ranged from 14,625 to 29,452\/household in Incheon city and from 3,521 to 26,268\/household in Gwangju City. There was no significant change in energy cost according to the performing terms of flush-out between Incheon and Gwangju City.

• Journal of The Korean Astronomical Society
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• v.44 no.5
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• pp.143-150
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• 2011

This paper reports a characteristic motion of a polarity inversion line (PIL) formed at the solar surface, which is newly found by performing a three-dimensional magnetohydrodynamic simulation of flux emergence in the Sun. A magnetic flux tube composed of twisted field lines is assumed to emerge below the surface, forming a bipolar region with a PIL at the surface. A key finding is the successive half-turn rotation of the PIL, leading to the formation of a quadrupolar-like region at the surface and a magnetic configuration in the corona; this configuration is reminiscent of, but essentially different from the so-called inverse-polarity configuration of a filament magnetic field. We discuss a physical mechanism for producing the half-turn rotation of a PIL, which gives new insights into the magnetic structure formed via flux emergence. This presents a reasonable explanation of the configuration of a filament magnetic field suggested by observations.